This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-187969, filed Jul. 1, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a medical image processing device used in combination with various types of imaging diagnostic apparatuses, such as an ultrasonic diagnostic (imaging) apparatus, an X-ray computerized tomography (CT) apparatus, a magnetic resonance imaging (MRI) apparatus, a nuclear medical diagnostic apparatus and so on. More specifically, the present invention relates to an image processing device which is adapted to produce a composite image by subjecting two or more pieces of volume data obtained for the same region of a human body under examination through different imaging techniques to three-dimensional image processing.
The X-ray computerized tomography apparatus, one of medical imaging diagnostic apparatuses, is adapted to image the distribution of transmissions of X-rays through a human body under examination. The nuclear medical diagnostic apparatus is adapted to image the distribution of gamma rays emitted from a radioactive isotope taken by a human subject. The physical quantities of a human body for imaging vary according to types of medical imaging diagnostic apparatuses. Even one imaging diagnostic apparatus can image different physical quantities by switching its imaging modes. For example, the ultrasonic diagnostic apparatus generally has at least two imaging modes built in: B mode and Doppler mode. In the B mode, variations in transmission velocity of ultrasound within a human body are imaged as variations in brightness. In the Doppler mode, the velocity of a moving object, such as blood, and its flow rate are imaged.
In order to improve diagnosis accuracy, it is desired that doctors be able to observe some types of medical images having different physical characteristics and clinical values in combination. Heretofore, not only a single image has been displayed, but also images obtained by different types of imaging diagnostic apparatuses or images obtained in different imaging modes have been displayed side by side.
To be specific, in ultrasonic imaging diagnosis of, for example, a liver tumor, a B-mode image is used to identify the size, position and internal structure of the tumor and, at the same time, the positions of blood vessels running around the tumor are identified using a Doppler image. Thereby, the position relationship of the tumor and the blood vessels is identified. In addition, a blood vessel, which extends from a vegetative blood vessel giving nutrition to the tumor, is identified to determine the size of the vegetative blood vessels with respect to the tumor. Based on these results, the tumor is diagnosed with respect to the position, the degree of malignancy and the degree of progress.
Within the liver, arteries, veins and portal veins run three-dimensionally and intricately. In order to understand the relationship between the three-dimensionally running blood vessels and the tumor, doctors are required to have a high level of knowledge and experience. In giving medical treatment on the basis of the results of diagnosis, a doctor who made diagnosis must accurately present the relationship between the blood vessels and the tumor to a doctor in charge of treatment. In this case as well, a high level of knowledge and experience is required.
Thus, in ultrasonic imaging diagnosis of a liver tumor, a B-mode image and a Doppler image have been displayed in combination in order to allow doctors to readily understand the relationship between blood vessels running in three dimensions and the tumor.
At actual medical sites, an approach has been taken by which a two-dimensional Doppler image is displayed combined with a two-dimensional B-mode image. To further improve the diagnostic ability, an approach has been proposed by which a three-dimensional B-mode image and a three-dimensional Doppler image are respectively reconstructed from two-dimensional B-mode images and two-dimensional Doppler images which have been collected in a spatially continuous form and then displayed in combination.
Methods of producing three-dimensional medical images include surface rendering for displaying the surface extracted by means of thresholding from volume data in three dimensions, volume rendering for allocating an opacity or color to each of pixel values that make up volume data and displaying the data itself, and MPR which cuts out an arbitrary plane section from volume data and displays an image of that plane section.
According to the surface rendering, by extracting the surface of the tumor or blood vessels, their three-dimensional surface configuration, location and running state can be displayed. Likewise, in the volume rendering, by allocating a high level of opacity to each of pixels in regions corresponding to the tumor or blood vessels, their three-dimensional surface configuration, location and running state can be displayed.
However, according to surface rendering-based and volume rendering-based images, the three-dimensional configuration and the position of a target can be observed, but it is difficult to observe the internal structure of a tumor and blood vessels running within the tumor. On the other hand, with MPR-based images, the internal structure of a tumor can be observed by setting up a plane section in the tumor, but it is difficult to observe the three-dimensional configurations and positions of a tumor and blood vessels and the running states of the blood vessels within the tumor.
In three-dimensionally combining images of a liver tumor and images of blood vessels, a mere combination of surface rendering versions of B-mode and Doppler images, volume rendering versions of B-mode and Doppler images, or MPR versions of B-mode and Doppler images causes a problem that it is hard to understand the position relationship of the tumor and the blood vessels.
For this reason, a three-dimensional image display technique has been demanded which combines MPR versions of B-mode images and surface rendering or volume rendering versions of Doppler images and displays both the three-dimensional running state of blood vessels and the internal structure of a tumor simultaneously in an easily understandable manner.
In three-dimensional imaging, it may be supposed that a part of an MPR image of a plane section of a tumor is veiled from a point of view with a three-dimensional image of blood vessels. In such an event, it will become difficult to tell whether the displayed blood vessels pass through the cutout plane section of the tumor or run outside the plane section. This constitutes an obstruction to imaging diagnosis, failing to provide information useful in giving medical treatment.
It is therefore an object of the present invention to provide a three-dimensional medical image composite display device which produces an image useful in imaging diagnosis and treatment by performing three-dimensional image composition processing on two or more types of volume data obtained for the same region of a human body under examination through different imaging techniques.
According to the present invention, there is provided a medical image processing device for producing a plurality of three-dimensional images for the same region of a human body under examination and combining the three-dimensional images to produce a composite image for display, comprising:
input means for setting a plane section of the region of the human body under examination;
first image projection means, responsive to first three-dimensional data for the same region of the human body under examination, for producing a three-dimensional image containing the plane section set by the input means;
input means for specifying the display/non-display of a region of the human body under examination;
second image producing means, responsive to second three-dimensional image data for the same portion of the human body under examination, for producing a three-dimensional image having data on one side of the plane section removed; and
combining means for combining the three-dimensional image containing the plane section produced by the first image producing means and the three-dimensional image produced by the second image production means.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.